Hudson always disliked man accused of killing her family

Grammy and Oscar-winning singer and actress Jennifer Hudson has testified that she had known the man charged with killing three members of her family since they were in middle school together, but never liked him.

She was the first witness called at the murder trial of William Balfour, who is charged with shooting dead Hudson's mother Darnell Donerson, 57, her brother Jason, 29, and her nephew Julian King, seven.

Balfour was married to Hudson's sister Julia.

He did not treat his wife or his son Julian King well, Hudson testified.

"I would tell her (Julia) over and over again not to marry William," she said.

Hudson testified about the harrowing day - October 24, 2008 - when she learned that her mother and brother were dead and her nephew was missing.

She flew home to Chicago and identified her mother and brother's bodies at the morgue.

On October 27, she was back at the morgue to identify her nephew's body.

Before Hudson moved out in the summer of 2006, the family had lived together in the same house in Chicago where the bodies of her mother and brother were found.

Julian King's body was found in a white SUV that Hudson had bought for her brother Jason.

Prosecutors say Balfour stole the vehicle, killed Julian in the back seat, and then abandoned it.

The murder weapon, a handgun which had been stolen from Hudson's brother Jason, was found in a vacant lot near the SUV, according to prosecutors.

In opening arguments at the trial, attorney Veryl Gambino described Balfour as a jealous and vindictive man who repeatedly threatened to kill Julia Hudson and her family.

"These weren't just words. They weren't just threats. They were deadly warnings of what was to come," Ms Gambino said.

If convicted, Balfour could face life in prison.

Hudson burst onto the music scene in 2004 when she performed on the television singing contest American Idol.

She subsequently won a Grammy for her debut album, and an Academy Award for her role in the movie Dreamgirls.

Defence lawyer Amy Thompson said during her opening statement that Balfour's DNA was not found on the murder weapon, or inside the SUV where Julian King's body was found.

She said the Chicago police knew the media would "explode" about the case because of the link to Hudson, and in their haste got the wrong man.

Ms Thompson told the jury that Jason Hudson was a drug dealer and had been shot twice previously, causing him to lose part of his left leg.

The police "did nothing to determine if it might have been Jason Hudson's violent business that led to him getting shot twice before, that led to these murders," Ms Thompson said.

She also noted that the Hudson family lived in Englewood - "probably the most dangerous neighbourhood in Chicago".

Asked during cross-examination if she knew what her brother did for a living, Jennifer Hudson said: "I don't really know."

Julia Hudson married Balfour in December 2006 - without telling Jennifer or Jason Hudson or their mother.

Julia Hudson testified that her husband became jealous when she got gifts from other people, and was jealous even of her son, telling Julian King not to kiss her.

She separated from Balfour in February 2008, but three months later he begged her to come back.

When she said she could not, Balfour said he would kill her family.

"If you leave me, you'll be the last to die," Julia Hudson said Balfour told her.